Gantry crane



June 11, 1957 B. E. BLANCHARD ETAL 2,795,338

GANTRY CRANE 3 Sheets-Sheet 1 Filed Aug. 27, 1956 will! June 1957 B. E. BLANCHARD ETAL 2,795,338

GANTRY CRANE 3 Shets-Sheet 2 Filed Aug. 27, 1956 22 /Z Z Z! June 11, 1957 B. E. BLANCHARD EI'AL 2,

GANTRY CRANE Filed Aug. 27, 1956 3 Sheets-Sheet 3 ANTRY CRA Bernard E. Blanchard and Anders H. Brolin, Green hay, Wis, assignors to Northwest Engineering Corporation, Green Bay, Wis., a corporation of Wisconsin Application August 27, 1956, Serial No. 606,473 6 Claiuns. .(Cl. 212 -59) The invention relates to traveling cranes and more States Patent particularly to traveling cranes having a collapsible gantry. a

The gantry of a crane is a frame structure associated With the usual A-frame of a crane to shift the point of attachment of the boom hoist system as far as possible from the boomhinge point. The point of attachment of this system is usually to the A-frame but with a gantry this point .of attachment is shifted to a point above the A-frame end and to the rear of the crane which has the advantage'of reducing boom hoist tension and decreasing the boom compression stresses. ductionlin boom compression allows the use of a lighter boom structure and, for a given weight of machine, allows ea r W k Hg e ds t be h d ed a th po of the boom. Gantries, however, increase the overall height of the crane when in working position. In a mobile unit, it is desirable, for transportation reasons over the highways or in industrial plants, to keep the height down to a minimum. The main object of the invention is to provide a gantry which may he collapsed from its upper operating position to a lowered transporting position in a simpleman ner and without danger to operating personnel.

A further object of the invention is to provide a gantry which-may be quickly raised to operative position or lowered to inoperative position by the .power of the machine n cke or loc ed in these Po n by the insertion or removal of two pins, thus saving valuable time when the machine is used on a rental basis, the arrangement being such that during raising and lowering operation of the gantry no personnel need be in the area of the gantry to guide or hzmdlethe gantry parts. Only after the raising or lowering operation is completed by the machine operator from position in the cab need any one return to the area of the gantry to reinsert the locking pins, and this may be done by the machine operator himself, if desired.

A further object of the invention is to provide a gantry whose parts may be quickly raised or lowered "by the power of themachine and, whenso raisedor lowered,

will be maintained in either of these positions, and through the use of cooperative stops the parts to be locked by the pins are assured of accurate alinement-for the insertion of the pins.

This application is a continuation in part of our application Serial No. 552,491, filed Dec. '12, 1955, and

broken .away;

Patented June 11, 1957 Fig. 2 is a view similar to Fig. 1 showing the gantry in another operating position;

Fig. 3 is a view similar to Fig. 1 showing the gantry structure in a traveling position;

Fig. 4 is an enlargedside elevation view of the gantry; Fig. 5 is an end elevation view of. parts of the gantry; Fig. 6 is a plan view of the gantry, parts being broken away and parts being shown in section;

Fig. 7 is a plan view Showing the boom hoist cable reeving. I

Referring to Fig. 1, we have shown a crawler type crane C having a rotating base 7 with a boom 8 pivotally mounted at 9 on said base, this base being provided with the usual Arframe 10 that carries a shaft 11 providedwith pulley 12 at-its'opposite ends over which the leads of 'a boom hoist cable 13 run, said cable being connected at one end to the machinery frame side and at the other to a hoist drum 1.4.

The gantry structure embodying the invention includes compression struts or frame members 15, oneat each sideof the frame, each supported at its front end on the shaft 11 andconnected by bolts 16 to the upper angled end 17 of a companion upright tension frame member 18 mounted at 19 on a side of the rear portion of the base of the machine, the two frame members and the two frame members 18 forming a fixed frame structure. The angled end 17 of each frame 18 is provided with laterally disposed projections or stops 2t) and with a vertically disposed projection or stop 21.

.The movable portion of the gantry comprises a cable carrying tension frame member 22 which at its outer end,- by means of pins 23, carries the boom hoist sheave bridle 24 including the sheaves 25 and the floating boom hoist bridle 26 including the sheaves 27 and 28 for the cable 13 indicated in Fig. 1. The boom hoist cable system also includes a cable 29 connected at one end to the outer end of the boom and at its other end to the bridle 26. At its inner end, the member 22 is connected by a pivot shaft 30 to the outer end of a compression frame member 31 that is pivoted at its outer end to the shaft 11. Members 22 and 31 are fabricated structures as shown in Fig. 6, the outer end of the member 31 having angled forked portions 32 between which a stop block 33 is mounted. A pair of links 34 and 35 on each side of the machine form a connection between the fixed parts of the gantry frame and the members 22 and 31.

The links 34 are single links while the links 35 are double links as will'be seen fromFig. 5. The upper end of each link 34 is pivotally connected to the shaft 30 to which the outer ends of members 22 and 31 are connected. "The lower end of each link 34 is pivotally connected by a pin 36 to one of the ends of the double links 35 whose other ends are connected by a pin 37 to the adjacent frame member 18. The links 34 and 35 form a collapsible or foldable supporting means which permits the members 22 and 31 to be positioned in a raised or lowered position. i

i For the raised position of the members 22 and 31, each of the double links 35 has a centrally or medially disposed hole38 adapted in the position shown in Figs. 1 and 4 to register with a hole 39 in the upper end of the frame member 18 to receive a pin or bolt 40. Alinement of the holes 38 and 39 is assured by the fact that pads or stop portions 41 on the links 35 contact the stops 20 on the members 18 when the links 34 and 35 are in raised position.

For the lowered position of the members 22 and 31, the angled end portions 32 of the frame member 31 have holes .42 therein adapted to be alined with the holes 39 in the frame members to receive the pins or bolts 40 3, when the parts are in the lowered position shown in Figs. 2 and 3. Alinement of the holes39 and 42 is assured by the fact that the stops 33 on the member 31 contact the stops 21 of the frame members 18 when the links 34 and 35 are in their folded position. i

The links 35 are preferably of curved form to bring the three pins 30, 36, and 49 into' substantial alinem ent to remove bending stresses from said links when they are in their upper operating positions, putting thatpart of the links 35 between the pins 36 and 40 in simple tension. This resolution of the forces acting on these links also acts to put the members 18 in simple tension and remove bending stresses therefrom.

When in the above described construction, with parts shown in Fig. 3, the pins 40 are removed to 'free the member 31 from its fixed connection with the fixed frame parts of the gantry, the boom 8 then either resting on the ground or blocked up to a horizontal position, operation of the boom hoist system through the turning of the drum 14 to wind in on the hoist cable 13 acts through the bridle 24 and the member 22 to raise' or swing the outer end of the member 31' upwardly from its lowered position shown in Fig. 3 to its upper position shown in Figs. 1 and 4 causing the links 34 and 35 to swing from their, folded position relative to each other to their extended position to bring the stops'41 into contact with the stops 20 and bring the holes 38 of the links 35 into position alined with the holes 39 in the uprights 18 so that the pins 40 can be inserted through these alined holes to hold the linkages in their extended position. and elevate the tension rnember 22 relative to the machine base and the fixed parts 15 and 18 of the gantry to displace the boom hoist cable anchorage as far as possible from the front of the machine and above the A-frame pin shaft 11 to reduce boom hoist tension and decrease the boom compression forces. This elevating of the gantry while the boom stays lowered is etfected through the pull exerted in the boom hoist cable 13 working through a lever arm indicated at 43 which is equal to the displacement of the pins 30or 23 from the shaft 11. The weight of the boom is normally enough to produce suificient tension in the boom hoist system when acting through said lever arm to overcome the backward movement of the parts .22, 31, 34, and 35 about the pivot shaft 11.

Only after the raising or lowering operation is completed by the machine operator from his position in the cab need any personnel return to the gantry to reinsert the, locking pins, and since no one is required to guide or handle the gantry frame parts prior to or during the raising or lowering operations, the insertion or removal of the pins may be done by the machine operator himself, if desired. It is also to be noted that the pinning of the gantry in its lowered position completely eliminates the links 34 and 35 from. the strength triangulation. Since all the movable parts of the gantry including the links 34 and 35 are always connected together, there is no danger of the operator getting caught or struck by parts of the gantry.

The load line 44 extends over a sheave on the outer end of the boom 8 in the usual manner and is mounted at its other end on its hoist drum 45.

We desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in. the claims.

What we claim as our invention is:

1. Ina crane, the combination of a base, an A-frame mounted on the base, a boom pivoted on the base, a hoist cable system for raising and lowering the boom, a gantry comprising a fixed frame extending rearwardly from the upper portion of said A-frame and including uprights at the rear of the crane body, a swingable member pivotally connected to the said fixed frame where it connects with said A-frame, and extending rearwardly to the back of the '4 the crane, a boom hoist cable carrying member pivotally connected at its rear end to the rear end of said rearwardly extending member, and sets of foldable links movable from a folded to an extended position operatively connecting said rear end of said rearwardly extending member and said cable carrying member to said uprights for controlling the movements of said rearwardly extending member at all times, to permit raising said members to an elevated position through tensioning of the hoist cable of said system while the boom is in a lowered position, each set of links being a pair of links pivotally connected together at one of their ends, the other end of one of said pair of links being pivotally connected to the rear end of said swingable, member, the other end of the other of said pair of links being pivotally connected to said uprights, means for locking one of the links of said sets of links to said fixed frame of the gantry when said members are in elevated position and said links are in an extended position, and means for locking ,said rearwardly extending member directly to said fixed frame of said gantry when said rearwardly extending member and said anchorage member are in theirlowered position and said links are in their folded position.

2. The crane structure as defined in claim 1, wherein the means for locking one of the links to the fixed frame of the gantry and for locking the rearwardly extending member to said fixed frame of the gantry include a set of removable pins.

3. The crane structure as defined in claim 1, wherein the links that are locked to the fixed frame of the gantry inthe elevated position of said members are of curved form, to put said links solely in tension when so locked.

4. In a crane, the combination of a base, an A-frame mounted onsaid base, a boom pivoted on said base, a hoist cable system for raising and lowering the boom, a gantry comprising a fixed frame, extending rearwardly from the upper portion of said A-frame and including uprights at the rear of the crane body, a swingable member pivotally connected to the fixed frame where it connects with said A-frarne and extending rearwardly to the back of the crane, a boom hoist cable carrying member pivotally connected at its rear end to the rear end of said swingable member, and sets of foldable links movable from a folded to anextended position and operatively connecting said rear end of said swingable member and said cable carrying member to said uprights for controlling the movements of said rearwardly extending member at 'all times and permitting raising said members to an elevated position through tensioning of the hoist cable of said system while the boom is, in a lowered position, each set of links being a pair of links pivotally connected together at one of their ends, the other end of one of said pair of links being pivotally connected to the rear end of said swingable member, the other end of the other of said pair of links being pivotally connected to said uprights, the links which are pivotally connected to said uprights having apertures intermediate their ends and said uprights having apertures alineable with said apertures in said links, pins insertable in said apertures when said sets of links are in their extended position and said swingable member is in raised position to hold said links in extended position, said swingable member having parts provided with apertures also adapted to aline with the apertures above named in said uprights to receive locking pins for locking said swingable member directly to said fixed frame when said sets of links are in folded position and said swingable member is inits lowered position.

5. The crane structure. as defined in claim 1, wherein the means for locking .one of the links of said sets of links to the fixed frame of the gantry is a removable pin for insertion in alined apertures in said link and the fixed frame of the gantry and said ,apertured links have stop portions adapted to abut stops on the fixed frame of the gantry when said links are in extended position to insure alinement of said apertures for receiving said pins.

6. The crane structure as defined in claim 1, wherein the means for locking the swingable member to the fixed frame of the gantry are removable pins for insertion in alined apertures in the outer ends of said swingable member and in the frame of the gantry and said swingable member has stop portions adapted to abut the stop of the fixed frame of the gantry when said swingable frame is in its lowered position to insure alinement of said apertures for receiving said pins.

No references cited. 

